The present invention relates to a spacer construction for gas insulated, high voltage cable, the cable including an outer corrugated tube and an inner conductor located centrally in the corrugated tube and held therein by means of spacers.
Gas insulated cables are known, having an outer, tubular envelope, and an inner conductor held therein by means of spacers. These cables come in lengths of e.g. a few meters. The spacers are usually disc shaped with a central opening for slipping such a disc onto the conductor and being secured thereto. The outer tube is then pushed on top of the proposed conductor-plus-spacer configuration. Long cables require in toto several hundreds of such spacers which render the entire manufacturing procedure quite cumbersome. Even spacers which are cast or extruded over the inner conductor are not too much of an improvement as far as ease of manufacturing is concerned.
High frequency cable when used as transmission lines for rather high power, and particularly when used for considerable length, are also constructed to have an inner conductor and a tubular, corrugated outer conductor, and spacers are included each of which having three similar, insulative support elements arranged regularly about the conductor and interconnected by a resilient, open loop wire. Since such a spacer does not have a closed annular configuration, it can be slipped laterally onto the conductor, one upon the other just ahead of folding a metal strip longitudinally about the inner conductor-plus-spacers to form the tubular outer conductor in a continuous process. The edges of the strip adjoin after the folding process and are welded together. The same procedure is hardly realizable for high voltage cable because of the metal holder for the spacer and support elements. Even if a suitable replacement could be found, upon arc developing for a voltage breakdown, spreading of the resulting decomposition products cannot be avoided. Consequently, a considerable length of such a cable will have to be replaced because damage must be expected to have spread extensively.